The phenomena of electron-positron pairs production through the polar cap region of a magnetar is studied. Assuming the distances of electron-positron pair regions from the magnetar centre to be the height scales of magnetic deformed regions and hence determine by adopting the Alfven waves propagation. The maximum potential drop on the magnetar surface and the potential differences in the confined regions are obtained by using Lorentz factor. The attempt is made to find out the curvature photon energy through the polar cap region of magnetar that is greater than critical energy and verify the conversion into electron-positron pairs via synchrotron radiation with their characteristic photon energy. Further, an estimate is made to flow the charged particles per second through the polar cap region.